Answer:Hence, correct option is I & IV.
Explanation: 
Ionic compounds have following properties:
- They are hard.
 - They from crystal lattice.
 - They exist in crystalline form of solids
 - They are ionic compounds and highly soluble in water.
 
So, from the above mentioned properties of the ionic compounds the properties of ionic compounds asked in a question are (I) and (IV).
Hence, correct option is I & IV.